UPPER MERION — For the first 22 games of the 2013 season, Ray Gaddis’ name was penciled into the left-back spot on the Philadelphia Union’s starting XI.

Without fail, 22 times out of 22, the second-year, second-round draft pick was John Hackworth’s go-to guy.

So when Gaddis had to sit on the sidelines for two games with a high ankle sprain that forced him off the field at halftime of the Aug. 3 game against Chicago, his reaction to getting back on the field wasn’t one of hesitation or anxiety. It was the same desire to prove something that has guided him all season.

“I think there’s pressure in any situation, not necessarily because of him relying on us,” Gaddis said Tuesday. “(Hackworth) believes in us and thinks we’re good enough to play there. We have the most shutouts in the league, but that gets overlooked a lot of times and he gets a lot of criticism, but no one says anything about that. He’s a tremendous coach, and it’s just been a great experience for the younger players.”

Perhaps as much as anyone, Gaddis is emblematic of Hackworth’s selection this season. Despite the likes of Bakary Soumare and Gabriel Farfan languishing on the bench before recouping them for value in trades, the second-year Union manager stuck to his young guns at the back.

Save for a red card against Seattle and subsequent one-game suspension, Sheanon Williams has played every minute this season, either at right back or deputizing in the center as he did in last week’s 0-0 draw against Montreal. The ankle injury to Gaddis was just the third time he’d left a game all season, the earliest prior change coming in the 79th minute. And Amobi Okugo’s red card, leading to a two-game suspension that stretches through this Sunday’s trip to San Jose, was the first minute he’d left the field since Hackworth took over as manager 14 months ago.

Those numbers may not be unusual, until you consider that of those three players, Gaddis is the oldest, having turned 23 in January.

That youth has served the Union’s defense and serves as a rallying point for a perpetually underestimated unit.

“It does help our mentality. I think us being so young and we’re all pretty close on and off the field, I think as the season has gone on, we’ve gotten better and better,” Gaddis said. “… It definitely makes us hungrier as younger players to see that if we can do what we’re doing now, we definitely can get better in every aspect.”

Gaddis in particular shined in the blanking of Montreal last week. Shifting over to right back — replacing Williams as he slid centrally to compensate for Okugo’s absence — Gaddis muted former Union midfielder Justin Mapp, a week after Mapp terrorized Houston in a 5-0 thrashing by the Impact.

As a unit, the Union limited Montreal to just four shots, one on goal, in shutting out the Eastern Conference leaders for the Union’s fifth clean sheet in seven games and league-leading 10th this season.

Despite those numbers, Gaddis knows that few in the league see the Union for the defensive team they’ve become.

“It’s definitely a motivational point,” Gaddis said. “We don’t talk about it too much, but quietly everyone knows. We’re all on the same page. We know what we’re doing. … Of course you feel like, hey, we should get some respect. But hey, when we go out there, we’ve just got to continue to go out there and do our jobs.”

For more on the Union, visit Matthew’s blog at uniontally.blogspot.com.